Hilary was scuba diving. She was 30 feet below the surface when she swam toward the five platform. She dropped her camera when she was 10 feet from the surface and had to swim down 15 feet to get it. At what elevation did Hilary retrieve her camera??

-25

Step-by-step explanation:

Hilary started off at -30 feet below sea level, and she dropped her camera when she was 10 feet away from the surface. Which meant she rose 20 feet, and she was -10 when she realized she dropped the camera, she went back down -15 feet. By that time she was -25 feet below.